1. Field of the Invention.
This invention relates in general to a method of preventing mobile phone fraud, and more specifically, to a method of preventing mobile phone fraud using an exchange of radio frequency signatures between mobile phone systems.
2. Description of Related Art.
Mobile phones combine the mobility of the radio link and the world-wide land telephone network to provide a communication link to any other telephone in the world. However, as mobile phones have become more prevalent throughout the country, fraud has become a major problem. Fraud robs service providers of hundreds of millions of dollars every year. Like all crimes, there are several varieties of fraud, including "cloning."
Cloning fraud, which occurs when a legitimate subscriber's mobile identification number/electronic serial number (MIN/ESN) combination is used for illegal purposes, is among the most sophisticated and difficult forms of fraud to prevent. Often, the pirate will use simple electronic devices to "capture" the legitimate MIN/ESN combination during its transmission by radio frequency (RF). In these cases, the legitimate subscriber often does not know fraud is being commited with his or her MIN/ESN combination until they receive their bill. This is currently the most popular method of gaining illegal access to a mobile phone system, because the legitimacy of the stolen MIN/ESN combinations makes cloning difficult to catch.
Often, cloning fraud occurs outside of the home area of the subscriber. Once the MIN/ESN information has been cloned, the MIN/ESN combination is valid for access to the mobile phone system anywhere. Roamer fraud is committed by a local thief using a MIN/ESN imported from another service area, and thus not representing a true roaming subscriber. The exploited MIN/ESN is usually gathered through the use of a MIN/ESN reader in a home service area for the mobile phone.
It can be seen, then, that there is a need for more effective techniques for preventing mobile phone fraud, especially roaming mobile phone fraud. Furthermore, such techniques must be easy and inexpensive to implement, and must not put unacceptable demands on subscribers.